Composition of matter effluent from refiner of a wet laid process

Abstract

A composition and process for making the composition by co-refining: fibrillated virgin cellulose fibers, waste/recycle cellulose fibers, or both; co-refined cellulose ester (CE) staple fibers having a denier per filament (DPF) of less than 3 and the weight percent of CE staple fibers is less than 30 wt. %, based on the weight of CE staple fibers and said cellulose fibers; and water. The composition can be co-refined to obtain lower Canadian standard freeness yet improved drainage and wet laid products having good tensile strength, air permeability, stiffness, burst strength, and bulk.

What we claim is: 
     
       1. A process comprising refining a feed composition fed to a refiner, said feed composition comprising:
 a. virgin cellulose fibers, waste/recycle cellulose fibers, or both, and 
 b. cellulose ester (CE) staple fibers at a weight ratio of cellulose fibers to CE staple fibers of more than 3:1, said CE staple fibers having:
 i. a denier per filament (DPF) of less than 3, 
 ii. a cut length of less than 6 mm, 
 iii. crimping, and 
 iv. a non-round cross-sectional shape, and 
 
 c. water. 
 
     
     
       2. The process of  claim 1 , wherein the co-refined CE staple fiber is not fibrillated after refining, or has an average of not more than 2 fibril/staple fiber after refining. 
     
     
       3. The process of  claim 1 , wherein no surface hydrolyzing binder is added to or contained in the feedstock composition, or the CE staple fibers in the feedstock composition are not surface hydrolyzed. 
     
     
       4. The process of  claim 1 , wherein the fibers have a curl value at least 16, as determined by a Metso FS5 Fiber Analyzer. 
     
     
       5. The process of  claim 1 , wherein the CE staple fibers have a cut length, and the ratio of cut length to DPF is not more than 2.5:1. 
     
     
       6. The process of  claim 1 , wherein no plasticizer is added to the feedstock composition. 
     
     
       7. The process of  claim 1 , wherein the CE staple fibers are obtained by cutting filaments, and the filaments have an untwisted fiber to fiber coefficient of dynamic friction between 0.11 to 0.20 and a fiber to metal coefficient of dynamic friction of not more than 0.70. 
     
     
       8. The process of  claim 1 , wherein the CE staple fibers have:
 a) a crimp frequency of 10 to 30 CPI, or 
 b) a crimp amplitude of at least 1.0 mm, or 
 c) an average effective length that is not more than 75% of the actual length, or 
 d) a retained tenacity of at least 80%, or 
 e) a CPI:DPF of 5:1 to 14:1, or 
 f) any combination of two or more of the above. 
 
     
     
       9. The process of  claim 1 , wherein the feed composition to the refiner comprises waste/recycle cellulose fibers. 
     
     
       10. The process of  claim 1 , wherein the consistency of the composition fed to the refiner is not more than not more than 7 wt. %. 
     
     
       11. The process of  claim 1 , wherein the composition is refined at a refining intensity between about 0.1 and about 0.3 Ws/m per pass. 
     
     
       12. The process of  claim 1 , wherein the refiner operates at a specific edge load of between about 0.75 to 4.5 Ws/m. 
     
     
       13. The process of  claim 1 , wherein the CE staple fibers have a multi-lobal cross-sectional shape. 
     
     
       14. The process of  claim 1 , wherein the CE staple fibers have a DPF of 1.0 to 2.5.